Walkthrough Checklist

This section provides a checklist of things to look for while at the facility . It provides an overview of the major boiler energy opportunities. It is designed to help assure that major savings opportunities are addressed, and to help identify areas on which to focus more detailed analysis.

Click on applicable check boxes for more information and specific opportunities:

• Is the stack temperature too high?
  • Optimum stack temperature is typically 50°F to 100°F above saturated steam pressure at high fire in a saturated steam boiler.
  • A record of the stack temperature after boiler tuning offers a more accurate target for optimum  operation.
  • Stack temperatures higher than these suggest poor heat transfer or too much combustion air.
  • Stack temperatures lower than 275 °F can lead to corrosive condensation.
  • Tune the Boiler. (Reduce excess combustion air)
    • Be sure not to reduce excess air below minimum required to avoid creation of carbon monoxide.
  • Clean the boiler to remove water side and fireside fouling.
    
    • Soot can usually be removed with a brush during regular maintenance.
    • Scale on the water side may require extensive chemical treatment if deposits are severe.
  • Preheat combustion air.
    
    • Stack gas temperature should typically be over 400°F on a well tuned boiler for this to pay off.
• Is the boiler operating at incomplete combustion?
  • Incomplete combustion is difficult to ascertain without a stack gas analyzer. Excessive soot buildup, or fuel consumption for the boiler load might be an indicator. A stack gas analyzer will allow the operator to compare O₂ and CO₂ levels to optimum levels for efficient operation.
  • Tune the Boiler. (Reduce excess combustion air)
    • Be sure not to reduce excess air below minimum required to avoid creation of carbon monoxide.
• Does the boiler cycle frequently?
  • Boiler efficiency is reduced at partial load. Frequent cycling reduces the overall operation efficiency and the life of a boiler. Continual cycling can be an indicator of an oversized boiler.
  • Install multiple smaller boilers (modular).
  • Match steam load to the boiler output.
• Are there any opportunities for heat recovery?
  • Install heat exchangers to use the stack gases to preheat the boiler make up water.
    • Waste heat from air compressors or other equipment can be used for this application. Use high pressure condensate to create flash steam for low pressure heating service.
• Is the blow-down of the boiler water manually controlled?
  • As water is evaporated to steam, solids in the water remain in the solution. To keep dissolved solids from building up to excessive levels, the boiler water is drained and replaced with fresh water. This is called “blow-down.” The difference in temperature between the replacement water and the hot boiler water represents an energy loss. To minimize this loss, blow-down should be set to the minimum required to keep dissolved solids at an acceptable level. The rate of continuous blow-down depends on the quality of the feedwater and the amount of condensate return.
• Is the flow rate of the induced draft and forced draft fans being controlled by throttling methods?
  • Install VSD control on boiler induced draft and forced draft fans.
    • Boilers typically operate 24 hours a day, 365 days per year. Improving the efficiency of any equipment associated with the day to day operation of the boiler will produce significant energy savings.
• Is the efficiency and performance of the steam system being monitored manually?
  • Install a boiler stack gas thermometer with a maximum indicating hand.
    
  • Install a meter to measure the amount of boiler make-up water being consumed.